Milk frother appliance, drinks preparation system and a drinks preparation machine

ABSTRACT

An appliance for preparing frothed milk includes a container for receiving milk, and an electrically operated drive for delivering and/or frothing the milk. The appliance includes a docking element for connection to a drinks preparation machine. The docking element includes a connection for steam delivered by the drinks preparation machine,—an interface for electrical current supplied by the drinks preparation machine, and a milk froth outlet for the frothed milk.

BACKGROUND OF THE INVENTION Field of the Invention

The invention generally relates to the field of appliances for preparingdrinks and, more particularly, to an appliance for producing milk frothand milk drinks, to a drinks preparation system as well as to a drinkspreparation machine.

Description of Related Art

Milk frother appliances as integrated modules of coffee machines or asseparate appliances that are dockable onto coffee machines are known. EP2 047 779 discloses a coffee machine with a dockable milk module,wherein hot steam from the coffee machine is used to froth milk, whichis sucked out of a vessel of the milk module according to the Venturiprinciple. The frothed milk is dispensed via a pivotable arm. EP 2 220973 shows a coffee machine with a dispensing device for milk froth. Theacting manner of the dispensing device is likewise based on the Venturieffect, on account of which milk is sucked out of a separate vessel byway of hot steam injected into the Venturi nozzle, is swirled with airand is thus frothed up. The dispensing device is integrated into thehousing of the coffee outlet, but is arranged such that milk does notneed to be led further into the inside of the coffee machine, so thatits parts can be cleaned separately. Despite this, the principle isbased on milk being processed in the inside of the coffee machinehousing, which demands more effort on the part of the user for cleaning.

The appliances which are described above and which are based on theVenturi principle, however, are only capable of preparing hot milkfroth. However, the preparation of cold milk froth is often alsodesirable. WO 2014/044407 shows a device for the selective preparationof cold or warm milk froth, the device being able to be coupled onto thesteam outlet of a drinks preparation machine, for producing the warmmilk froth. The device has its own electricity supply connection. WO2011/144647 discloses a coffee machine with a removable, electricallydriven milk preparation module that is arranged on a base of the coffeemachine. The module is activated and supplied with current via a base ofthe coffee machine. The module has a pour-out, by way of which theprepared, in particular frothed milk can be filled into a vessel afterremoval of the module. With these solutions, the user must create themilk froth separately from the hot drink and, as the case may be,himself mix it with the hot drink—in particular coffee.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an appliance forproducing milk froth, which overcomes disadvantages of the state of theart and which is optimised for cooperating with an appliance forpreparing hot drinks, in particular with a coffee machine. A furtherobject is the provision of a corresponding drinks preparation machine,in particular coffee machine, which cooperates with the appliance, aswell as the provision of a system with an appliance for producing milkfroth and with a drinks preparation machine.

The appliance for preparing frothed milk includes a container forreceiving milk, and an electrically operated drive means for deliveringand/or frothing the milk. It is characterised by a docking element forconnection onto a drinks preparation machine, the docking elementincluding:

-   -   a connection for steam delivered from the drinks preparation        machine;    -   an interface for electrical current supplied from the drinks        preparation machine; and    -   a milk froth outlet for the frothed milk.

A particularly compact coupling between the drinks preparation machineand the milk frother appliance and one which is practical and simple inits handling is rendered possible by way of this approach. Due to thefact that the docking element also includes the milk froth outlet, thisoutlet in particular can be situated very close to the drinkspreparation machine, and can lie closely to the drinks outlet of thisdrinks preparation machine given a suitable design of this. The distancebetween the milk froth outlet and the drinks outlet in particular can besuch that a drinks vessel of common dimensions—for example a coffee cupor a Latte-macchiato glass—can be placed below both these outlets.

Typical drinking vessels for hot drinks with milk have a diameter of 6-8cm or more. The drinks preparation system with the milk frotherappliance and with the drinks preparation machine is preferably designedsuch that the distance between the hot drink outlet and the milk frothoutlet is so small, that such a vessel can be filled with the hot drinkand with the frothed milk in one and the same position. The distancebetween the hot drink outlet and the milk froth outlet is thereforepreferably maximal 5 cm, in particular maximal 4 cm or maximal 3 cm.Here, what is meant by the distance is the horizontal distance, i.e. thedistance of the exit points of the drink or the frothed milk, in aprojection along the vertical onto a horizontal plane. For the milkfrother appliance, this can mean that a distance between the milk frothoutlet on the one hand and an end surface of the docking element on theother hand, the end surface including the connection for the steam andthe electrical interface, is maximal 2.5 cm, in particular maximal 2 cmor maximal 1.5 cm

The docking element can be designed, for example, as a continuous,body-forming element, in the inside of which conduits for milk and steamrun. In an embodiment, it includes a body, wherein the mentionedconduits are designed as openings in this docking element body or arepresent in this as separate tubes or pipes. It can additionally includea housing. The leads for the electrical current then for example run onthe housing, in the housing and/or between the housing and the body.

In embodiments, the docking element body includes a main body with aplurality of fluid channels and a supplementary part, which isreversibly removable from the main body, wherein the supplementary partincludes a material, which is softer compared to the main body, iscontinuous and includes several elements, through which milk, steam,water and/or air can flow and which engage into the fluid channels.

In these embodiments, the supplementary part in particular can beconstructed as one piece from an elastically and/or plasticallydeformable, comparatively soft material. “Deformable” here, for example,means that the material can be manually substantially deformed by theaverage user without aids and without an excessive force effort.

The supplementary part can be designed, for example, as a silicone part.As is known per se, silicones are suitable for applications in the fieldof foodstuffs, since apart from their deformability, they can also beheated and are inert and can therefore be easily cleaned, for examplealso in a dishwasher.

The supplementary part in particular can be arranged in a manner atleast partly embracing the main body and can be unravelled from this. Itcan include an extensive or two-dimensionally frame-like base and onthis, the through-flow elements. The base of this supplementary part isthereby laid around the main body in a folded and/or bent manner.

Such a base of the supplementary part in particular can be formed fromflat sections with joints that are arranged between the extensive(flattish) sections. Such joints can be formed by slots and/or recessesin the base and be designed as rotation joints (hinges) with only onedegree of freedom.

The directions, in which flow can pass through the different elements,can be different, for example, by way of the elements being present atdifferent sides of the main body.

In embodiments, the supplementary part in particular is designed suchthat amongst others, it bears on two oppositely lying sides of the mainbody and includes elements for example of the mentioned type.

In embodiments, at least one nozzle and/or a valve is/are amongst theelements, i.e. the supplementary part forms at least one nozzle and/orvalve. The nozzle or the valve can project completely or partly into afluid channel in the main body or include a collar projecting into sucha channel. One example of a valve is a duckbill valve.

Such elements in the form of a nozzle and/or a valve form narrowings onaccount of their function, and the part of the fluid channel behind sucha narrowing is difficult to clean. However, a regular and thoroughcleaning is important for elements that come into contact with milk. Theapproach according to the invention permits these elements to be removedand exposed in a simple manner for the cleaning, by way of thesupplementary part being separated from the main body. Since thesupplementary part includes the several elements, despite this they alsoremain integrally together for the cleaning, do not get lost and can bere-inserted in simple manner, and specifically without incorrectassemblies being possible.

The main body can be manufactured, for example, of a plastic and bemanufactured, for example, in the injection moulding method, but othermaterials and manufacturing methods, for example ceramic materials orstainless steel, can also be considered. The main body can be of onepiece, but this is not a necessity. The main body, for example, can bemanufactured from a material block, wherein the fluid channels can belined with a material that is different from the material of thematerial block. One moreover also does not rule out the through-flowelements of the supplementary part engaging so far into the respectivefluid channels in the assembled condition, that these also form a liningof the fluid channels and at least regionally prevent a contact betweenthe fluid and the main body.

Apart from the advantage of the simple handling for the cleaning and forthe reassembly after the cleaning has been effected, the approach alsohas the advantage of an efficient manufacturability.

In alternative embodiments, the docking element body can also bedesigned as one piece, as the case may be with softer insert parts forpossibly required separate valves.

In the assembled condition of the drinks preparation system, the dockingelement can run between the drinks preparation machine and a main partof the milk frother appliance, and specifically above the drinks outlet.An end surface of the docking element, for example, can be essentiallyvertical for being brought into contact with a corresponding portion ofthe drinks preparation machine. The docking element can have anessentially cylindrical shape with a horizontal cylinder axisperpendicular to an end surface and with an arbitrary, for exampleessentially rectangular, cross section.

The milk frother appliance, for example, includes a mixing nozzle, inwhich the steam is brought together with the milk and, for thepreparation of warm frothed milk for example, also with air. Inembodiments, the mixing nozzle can be arranged in the docking element.In particular, the mixing nozzle can be arranged directly above the milkfroth outlet, i.e. the frothed milk gets into the milk froth outletdirectly from the mixing nozzle.

The milk froth outlet can form a milk froth outlet chamber that tapersdownwards. The milk froth of the frothed milk is further homogenised andchannelised in such a chamber.

In embodiments, the flow of the steam—which gets into the mixing nozzlefrom the steam connection—effects the sucking of air and the intermixingwith milk fed to the mixing nozzle, in a manner known per se, by whichmeans frothed milk can be produced, and this milk is warm on account ofthe heat released by the steam, wherein this heat is predominantly, butnot exclusively released to the milk as condensation heat. This suctioneffect can be based on Bernoulli's law (wherein the mixing nozzle canthen be designed for example as a Venturi nozzle) and/or on impulsetransmission, as is known per se in combination with so-called jetpumps.

The electrical current that is supplied via the interface serves for thedrive of an active element of the milk frother appliance, in particularof a pump, and in particular of a pump as part of a milk frothing unitfor the preparation also of cold milk froth.

In particular, the milk frother appliance can include a gear pump. Thegear pump at an inlet side is connected to a milk feed conduit and to anair feed, for the purpose of preparing frothed milk.

The milk frothing unit can optionally be designed such that an operatingparameter is adjusted in a manner depending on a measured value and/oroperator input. What is meant by “adjusting” here is exerting aninfluence upon the at least one operating parameter of the milk frothingunit that influences how this unit acts during an active milk frothingoperation. The adjustability therefore is different to a mere “on/off”,as is known from the state of the art. The adjustability in particularis effected such that a parameter, which is specified by the user and/orspecified by a control, has an influence on the characteristics and/orquantity of the produced milk froth. In particular, an adjustableoperating parameter can be a speed of the gear pump or the fed airquantity (which can be regulated, for example, by a valve unit with anadjustable valve opening).

Additionally to the mentioned connection for the steam, the dockingelement can include a further connection for water that is hot, forexample, and/or for steam, which is/are delivered by the drinkspreparation machine, the water or the steam being able to be used forthrough-rinsing and for cleaning. A conduit traversing the dockingelement can be present coming from this connection for the cleaningwater or for the cleaning steam. This conduit, for example, runs outinto the milk frothing unit, and as the case may be likewise serves forthrough-rinsing and, under certain circumstances also for sterilisingthe gear pump including the feed conduits and outgoing conduits.

In embodiments, the drinks preparation machine can also include an airdelivery location, through which air can be delivered to the milkfrother appliance, for example to its gear pump as the case may be, in aregulated manner. In such embodiments, the docking element canadditionally include an air feed-through for the air that comes from thedrinks preparation machine and which is to be delivered to the milkfrothing unit.

A drinks preparation machine, in particular a coffee machine of a drinkspreparation system of the type described here, can be designed as amachine of the type often called “capsule machine”, with a brewingchamber for inserting a portion capsule with an extraction material andfor brewing a hot drink (coffee or possibly tea or another hot drink)from this extraction material and water. However, it can also bedesigned, for example, as a bean-to-cup coffee machine with a millmechanism or as a piston machine for receiving coffee powder.

The drinks preparation machine for example includes a water container, awater pump and a water heater. A brewing chamber for preparing the hotdrink from heated water by way of extraction from an extraction materialis also present.

The drinks preparation machine is designed such that the milk frotherappliance can be docked onto it, by way of a steam delivery location anda machine-side electrical interface being present and being arrangedrelatively close to one another and such that the docking element can bedocked by way of a single predefined movement or a movement procedure(without parts which are moved relative to one another). Depending onthe design of the milk frother appliance, the drinks preparation machinecan moreover include an air delivery location of the previouslymentioned type, which is connected to the machine's internal valve unit,the unit in particular being electronically controlled.

The docking location with the steam delivery location and with themachine-side electrical interface (and air delivery location as the casemay be) in particular can be present in the direct proximity of thedrinks outlet. A distance between the drinks outlet and an end surfaceof the docking location, on which surface the respective end surface ofthe docked docking element abuts, can, for example, likewise be maximal2.5 cm, maximal 2 cm or maximal 1.5 cm.

A drinks preparation machine often has a front with a placement platformthat projects from the front and is for drinks vessel, and above this,likewise projecting from the front, with a drinks outlet hood, on whoselower side the drinks outlet is arranged. In embodiments, the dockinglocation is then present laterally on the drinks outlet hood. This, forexample, means that the milk frother appliance is coupled onto the drinkoutlet hood from the side.

At least the docking element and, for example, the complete milk frotherappliance is then arranged in front of the front of the drinkspreparation machine, in the coupled-on condition.

A drinks preparation system includes a milk frother appliance as well asa drinks preparation machine. The two appliances with regard to theirdimensioning are matched to one another such that the milk frotherappliance is either placed on the same level as the machine, or on amilk frother platform formed by the machine.

Moreover, the milk frother appliance as well as the drinks preparationmachine can be matched to one another with regard to their fashioning.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiment examples of the invention are hereinafter described by way offigures. The same or analogous elements are indicated in the figures bythe same reference numerals. There are shown in:

FIG. 1 is a view of the appliance for preparing frothed milk (milkfrother appliance);

FIG. 2 is an exploded representation of the milk frother appliance;

FIG. 3 is an exploded representation of the milk frothing unit of themilk frother appliance;

FIG. 4 is a view of the milk frothing unit sectioned along a horizontalplane;

FIG. 5 is a partial view of the seal of the milk frothing unit withelements of the gear pump;

FIG. 6 is a view of the upper main housing part of the milk frothingunit, which is sectioned along a horizontal plane;

FIG. 7 is a view of the upper main housing part from below;

FIG. 8 is a view of the upper main housing part, which is sectionedalong a vertical plane;

FIG. 9 is a view of the valve unit of the milk frothing unit;

FIG. 10 is an exploded representation of the valve unit;

FIG. 11a-11c show the valve unit in a plan view, side elevation andfront elevation, respectively;

FIG. 12 is a view of the milk frothing unit with a valve unit, fromabove;

FIG. 13 is a representation of the milk frothing unit, sectioned along aplane through the valve unit;

FIG. 14a-14b are views of the docking element, obliquely from above andbelow, respectively;

FIG. 15a-15b are views of the supplementary part;

FIG. 16a-16b are views of the main body;

FIG. 17a-17b are representations of the docking element without anexternal housing;

FIG. 18a-18c are representations of parts of the appliance, from whichthe function of the docking element is evident;

FIG. 19 is a view of the drinks preparation system with the milkfrothing appliance;

FIG. 20 is a detail of the drinks preparation system, representedsectioned along a vertical plane;

FIG. 21 is a detail concerning the docking of milk frothing applianceonto the drinks preparation machine;

FIG. 22 is a view of a detail of the milk frother appliance;

FIG. 23 is a schematic diagram of the drinks preparation system;

FIG. 24 is a sectioned representation of the milk frother appliancewhich is drawn only partly, with the docking element, in an alternativeembodiment; and

FIG. 25 is a view of this milk frother appliance in the alternativeembodiment.

DETAILED DESCRIPTION OF THE INVENTION

The appliance 1 for preparing frothed milk (milk frother appliance) isrepresented as a whole in FIG. 1. FIG. 2 shows an explodedrepresentation of its parts.

The appliance 1 includes a milk container 3, a milk frothing unit 5 anda lid 6.

The milk container 3 is designed in a doubled walled manner in therepresented embodiment, for thermal insulation purposes, butsingle-walled designs are also possible. It can be transparent orinclude a viewing window for checking the level of the milk.

The milk container 3 and lid 6 can be matched to one another such thatthe lid 6 can also be placed directly onto the milk container 3, withoutthe milk frothing unit 5 being arranged therebetween, by which means thefilled milk container with the lid can be placed into the fridge forexample. The milk container and the lid can also be cleaned in a simplemanner, and be designed, for example, in a dishwasher-safe manner.

The elements of the milk frothing unit 5 are represented in an explodedrepresentation in FIG. 3. A lower main housing part 11 carries anelectric motor 13 belonging to the gear pump, as well as an upper mainhousing part 14. A lateral window 12 is formed in the upper main housingpart.

The upper main housing part 14 forms a roughly circularly cylindricaltrough, in which gears 17 of a gear pump are arranged. The gears 17 ofthe gear pump are driven via a shaft 19, which is connected to theelectric motor 13. A seal 21 seals the trough to the bottom.

Additionally to the gears, the shaft and the electric motor, the gearpump can also have its own housing, or such can be integrated into themain housing or other parts, for example into a milk frothing unit cover16. In the represented embodiment example, the milk frothing unit cover16 is shaped out such that a pump chamber encompassing the gears 17 isformed between the seal 21 and the milk frothing unit cover 16, onaccount of an arching 15 (also clearly visible in FIG. 12).

A valve unit 20 is also fastened on the main housing 11, 14.

A milk suction tube 18 (not represented in FIG. 3) extends downwardsfrom the plane of the gear pump and projects into the milk container 3and almost up to the base of this, in the assembled condition of theappliance 1.

A connection shaped part 22 is further present beneath the gear pump.This part seals the window 12 and simultaneously forms a feed-throughfor connection of conduits of the milk frother, which are describedhereinafter and are fastened, on the one hand, to the main housing and,on the other hand, to a docking element.

Likewise visible in FIG. 3 are a spacer 23 and a motor seal element 24.

The docking element includes a docking element body, which is protectedby a docking element housing 26. The docking element body is formed by amain body 25 and a supplementary part 27, which is described in yet moredetail hereinafter. It can already be seen in FIG. 3 that thesupplementary part 27 includes a downwardly projecting milk froth outlet28.

FIG. 4 shows a view from above, of the milk frothing unit 5, which issectioned along a plane lying above the sealing plane defined by theseal 21. The lighter lines in the plan view represent elements runningfurther below, which per se are not visible.

The gear pump is attached above the sealing plane. An upper-side liquidconduit 31 leads to the gear pump. This is connected on the one hand tothe milk suction tube 18 and on the other hand to a hot water conduitand/or steam feed conduit 32, via duckbill valves 42, 41, which areformed by the seal 21 and are also clearly visible in FIG. 5. An airfeed conduit 34 is connected to the upper-side liquid conduit, which isto say to the gear pump at the inlet side, likewise via a duckbill valve43, which is formed by the seal.

Arranged behind the gear pump is a feed-through 36 for the deliveredmilk, which is already frothed, depending on the selected operatingcondition, through which feed-through this milk again goes downwardsthrough the sealing plane, where it gets through an outgoing conduit 35into the docking element.

FIGS. 6 to 8 show further views of the upper main housing part 14, whichin represented sectioned along a horizontal plane in FIG. 6 and along avertical plane in FIG. 8 and in a view from below in FIG. 7.

The lower-side conduits are formed by tubes of the connection shapedpart 22, which are laid into corresponding channels of the upper mainhousing part 14. These channels, i.e. the channel 51 for the hot waterand/or steam feed conduit 32, the channel 52 for the air feed conduit 34and the channel 53 for the outgoing conduit 35 are particularly clearlyvisible in the view from below according to FIG. 7.

The seal 21 (FIG. 8) is clamped between the upper main housing part 14and the milk frothing unit cover (not shown in FIG. 8). The pump chamberof the gear pump including the gears 17 is formed between the milkfrothing unit cover and the upper main housing part, due to the arching15 in the milk frothing unit cover (FIG. 3; FIG. 12).

A further optional feature can be seen in FIG. 8. The feed-through 36for the delivered milk that is already frothed depending on the selectedoperating condition is narrowed in the manner of a throttle. A certainbackpressure is produced in the gear pump by way of this, on account ofwhich pressure the flow quantity regulates itself. This backpressurecontributes to an efficient frothing of the cold milk.

FIG. 9 shows a view of the valve element 20, FIG. 10 shows an explodedrepresentation of the valve unit and FIGS. 11a-11c show the valve unitin a view from above, sectioned along the line E-E in FIG. 11a and alongthe line D-D in FIG. 11 a.

FIG. 12 shows a view of the milk frothing unit with a valve unit 20,without the docking element and milk suction tube, from above, and FIG.13 shows this sectioned along a vertical plane going through the line213 in FIG. 12.

The valve unit 20 includes two valve elements in a common valve housing61. Each valve element includes a closure element 62 that carries asealing element 63 and is movable along an axis—in the selectedinstallation situation—along the vertical axis. The upward movement iseffected by way of an electromagnet 64 and against the force of a spring65 stressed between the electromagnet (or the valve housing) and asecuring ring 66. The heads of the valve elements, which are formed atthe upper side by the closure elements and seal elements, projectthrough openings in the upper main housing part 14 (see FIGS. 12 and13). In the closed condition, a seal portion 67 of the respective sealelement 63 is pressed by the force of the spring against a surface ofthe upper main housing part 14, along the periphery of the respectiveopening.

With both valves, a valve chamber 71 forms in each case between therespective wall of the upper main housing part 14 and a seal 68. Aninflow opening forms when the closure element with the sealing element63 is lifted by the electromagnet, through which inflow opening air canflow from the outside into the respective valve chamber 71 and from thiscan get into a (common) air feed conduit through an air connection stubor branch 73.

The two valve elements can be actuated independently of one another andcan be opened in each case individually or together. Different valveopening conditions can be created by way of this. As a whole, four valveopening conditions result by way of either only one of the valveelements being open and the other closed, both being open or both beingclosed.

In embodiments, it can also be meaningful for the valve elements and/orthe size of the respectively formed inflow opening to be selected to adifferently large extent and/or for the air, which is admitted by one ofthe valve elements, to be subjected to a significantly greater flowresistance than the air admitted by the other valve element. The fourdifferent defined opening conditions are then quantitatively different.For example, the inflow opening of one of the valve elements can bedouble the size of the inflow opening of the other valve element, sothat the conditions “0” (air valve completely closed), “⅓” (the smallervalve element open), “⅔” (the larger valve element open) and “1” (bothvalve elements open) can be selected.

An airflow regulating element such a 3/2-way valve for example (notdrawn) and by way of which the path between the valve chambers 71 andthe mixing nozzle or the path between the valve chambers and the entryof the gear pump can be opened and the respective other path can beclosed, can be arranged in a manner connected downstream of the valveunit in the airflow direction, in order to regulate whether the mixingnozzle or the gear pump is to be fed with air. Such an airflowregulating element, however, can also be done away with, wherein theregulation is then effected automatically by the respective valveelements, by way of these only opening due to a vacuum at the outletside, and in this manner preventing a backflow of frothed milk into therespective path, which is not required.

The construction and manner of action of the docking element aredescribed hereinafter by way of FIGS. 14a-14c . FIGS. 14a and 14b showviews of the docking element obliquely from above and obliquely frombelow respectively. FIGS. 15a and 15b show the supplementary part 27 inan unfolded condition and FIGS. 15c and 15d in a folded condition. FIGS.16a and 16b show the main body 25. FIGS. 17a, 17b and 17c show thedocking element sectioned along the planes A-A, B-B and C-C in FIG. 17d. FIG. 18a shows a view of the appliance from above, and FIGS. 18b and18c show sections of sectioned representations of the appliancesectioned along the planes A-A and B-B in FIG. 18a , respectively.

The face-side end which, for example, lies at the front in FIGS. 14a and15c is coupled onto the coffee machined on operation, whereas theopposite end can be coupled onto the milk frothing unit 5.

The main body 25 as a whole can be designed as a shaped body of asuitable, heat-resistant plastic and be manufactured for example as aninjection moulded part. The supplementary part 27 is manufactured fromsilicone, for example. It is of one piece and as a whole is designed inan extensive (sheet-like) manner with functional elements that areintegrally formed thereon. The entirety of the extensive sections ishere indicated as a “base”. Joints 81, which are formed by continuousopenings, as well as groove-like recesses and which permit anunconstrained folding around the main body 25 are formed between theextensive sections 80. The dimensions of the extensive sections 80between the grooves are matched to the dimensions of the main body.

Apart from the milk froth outlet 28, the functional elements of thesupplementary part 27 are formed by feed-throughs 82-86, and a mixingnozzle element 89.

The main body 25 forms a feed-through conduit 96, which passes from theend at the coffee machine side to the opposite end and which is forcleaning water (cold or heated by the coffee machine) or cleaning steam,the water or steam when required going from the feed-through conduit 96into the hot water and/or steam feed conduit 32 and from this into theelements to be cleaned, in particular the gear pump. A feed-through 86,84 of the supplementary part is assigned to the feed-through conduit 96in each case at the coffee machine side and the milk frother side.

A steam connection, through which steam gets from the coffee machineinto the mixing nozzle, is also formed. The steam connection is formedby a feed-through 85 with an assigned valve 87 of the supplementary part27, the feed-through projecting into a steam connection opening 95 ofthe main body 25.

On the milk frother side, an opening 92, 93 for the supply of air andmilk and into which corresponding feed-throughs 82, 83 of thesupplementary part project are formed in the main body in each case. Theair feed-through 82 is provided with an assigned valve 88, and this isdesigned as a duckbill valve just as the steam valve 87 and is of onepiece with the remainder of the supplementary part 27.

For the mixing nozzle, the main body 25 includes a mixing nozzle opening99, into which the mixing nozzle element 89 projects. A milk frothoutlet continuation 91 and a positioning ring 94 surrounding this aremoreover formed on the underside and cooperate with a correspondingstructure 90 of the supplementary part.

The mixing nozzle is formed between the mixing nozzle element andcorrespondingly shaped chambers of the main body 25.

Steam which is fed in via the steam connection, via the valve 87 getsinto a mixing nozzle chamber 97, which one can see particularly well inFIG. 17c for example. A vacuum is produced in the mixing nozzle chamber97 by way of the flow of steam, by way of which vacuum air and milk issucked via the respective feed-throughs 82, 83 (FIG. 17b , FIG. 18b ).Milk froth arises in the mixing nozzle chamber, and goes downwardsthrough the milk froth outlet 28 and into a ready-and-waiting drinksvessel. The frothed milk is warm due to the condensation heat releasedby the steam.

On account of the small nozzle opening, through which the steam exits ata high speed, the mixing nozzle is thus designed such that a vacuum isproduced due to the nozzle effect. This also assists the transport ofmilk out of the milk conduit, even if the milk is actively delivered dueto the gear pump.

The duckbill valves 87, 88 are closed if normal pressure or a slightoverpressure prevails in the inside of the mixing nozzle chamber 97.However, they both automatically open if in contrast—as soon as steamflows in—a vacuum prevails on account of the Bernoulli effect and/or onaccount of impulse transmission.

The feed of air into the mixing nozzle chamber can also be effecteddirectly from the outside, for example via a duckbill valve, instead ofthrough the valve unit, wherein two air paths that are independent ofone another then result, on the one hand for the mixing nozzle chamberand on the other hand for the gear pump.

Such a design with the feed of air directly into the mixing nozzlechamber can also be selected for embodiments for example, with which,differing from the example described here, no electrically operateddrive means (no electrically operated pump) is present and with whichone froths merely in a steam-assisted manner, whilst utilising thesuction effect of the mixing nozzle.

The docking element is designed such that the milk froth outlet 28 canlie closely to the outlet for the hot drink. For this purpose, it isarranged in the direct proximity of the end surface 29 coupled to acorresponding surface of the drinks preparation machine. As discussedpreviously, the distance is not more than 2.5 cm and is preferably evenless. The distance as usual is measured as the distance measuredperpendicularly to the (vertical) plane defined by the end surface,between this plane and the centre point of the exit opening out of themilk froth outlet.

A further optional feature is particularly clearly evident in FIG. 17c .The outlet chamber 86, through which the—generally frothed—milk runsdownwards, tapers in the milk froth outlet 28. This on the one hand hasan additional froth-forming and froth-homogenising effect and on theother hand channelises the flow of milk or milk froth.

FIG. 19 shows a view of the complete drinks preparation system 100 withthe milk frothing appliance 1 and a coffee machine 101, onto which themilk frothing appliance 1 is coupled. FIG. 20 shows a detail concerningthis appliance, with the outlet hood represented in a sectioned manner.

The coffee machine, as is known per se for coffee machines, includes awater container, a water pump and a water heater. A brewing chamber forpreparing coffee from heated water by way of extraction from coffeepower is moreover present, the coffer powder being provided, forexample, in portion capsules which were previously inserted into thecoffee machine before the preparation. As an alternative to a portioncapsule system, the coffee machine can also be designed as a so calledbean-to-cup coffee machine, which also includes a coffee mill and grindsthe coffee powder in a portioned manner and feeds it to the brewingchamber. As yet a further alternative, particularly if the coffeemachine is designed as a piston machine, i.e. the brewing chamber isformed between a fixed part and a removable piston, one can yet alsoenvisage the coffee power being brought into the brewing chamber by theuser in a manner in which it is already in the ground, but loose(non-compacted) condition.

The coffee machine can further include a capture container for spentcoffee powder portions (in capsules or in a loose manner, depending onthe design of the coffee machine).

A placement platform 103 for placing a drinks vessel or cup is formed onthe coffee machine. This can be formed for example by way of a grating,below which a capture dish is located. In embodiments, the placementplatform can be height-adjustable in a suitable manner.

A coffee outlet 105, through which brewed coffee runs out and gets intothe cup or vessel lying therebelow, is located above the placementplatform 103. This outlet is located below an outlet hood 108 that formspart of the coffee machine housing and at least partly covers the outletto the front and to the sides.

The coffee machine 101 forms a front 106, from which, as is known per sefrom other coffee machines, on the one hand the placement platform 103projects and, on the other hand, above this, the outlet hood 108projects.

Here, a milk frother platform 107, onto which the docked milk frothingappliance 1 is placed, likewise projects from the front.

A connection location 110 for the connection of the docking element ontothe coffee machine is located in the proximity of the coffee outlet 105and here, below the outlet hood. This connection location includes asteam delivery location 111 for coupling onto the steam connection ofthe docking element, and a hot water and/or steam delivery location 112for coupling onto the feed-through conduit 83. The steam deliverylocation 111 and the hot water and/or steam delivery location 112 whenrequired are respectively supplied with steam and hot water from thewater heater, wherein a multi-way valve in the inside of the coffeemachine can selectively feed heated liquid or steam to the brewingmodule, the steam delivery location or the hot water and/or steamdelivery location 112.

The connection location further preferably includes electrical contacts113, which are represented schematically in FIG. 21. These electricalcontacts 113 form an interface on the drinks preparation machine side,and, given a coupled-on docking element, create an electrical connectionto corresponding electrical connection element contacts, which areconnected to electrical leads leading through the docking element or areformed by these. These electrical leads supply the electrically drivenelements of the milk frother appliance, specifically the gear pump, withelectricity and control signals as the case may be.

Thereby, it is possible to provide a control of these electricallydriven elements in the milk frother appliance (this appliance is thenprovided with the necessary electronic units and receives controlsignals from the coffee machine or from an input unit of the milkfrother appliance) as well as to accommodate a control of these elementsin the coffee machine itself. In the latter case, it is essentially onlycurrents driving the electrically driven elements in accordance with thesettings of the control, which are led through the electrical leads.

The docking of the milk frother appliance 1 is effected from the sideonto the outlet hood 108, and specifically such that the milk frotherappliance as a whole is arranged in front of the coffee machine andlaterally of the outlet hood 108. The docking is effected, for example,by way of a simple, linear, lateral movement of the assembled milkfrother appliance along the front 106.

As one can see in FIG. 21 (showing the milk frother appliance 1 in adecoupled condition) and in particular in FIG. 22 (milk frotherappliance without a coffee machine), the electrical leads and thecorresponding contacts 98 on the docking element side are formed on thedocking element housing 26. The leads can be formed by way of insulatedwires or strand conductors or by way of strip conductors of printedcircuit (circuit board or flexprint) or the like.

The control of the gear pump in particular is configured such that thespeed of the gears 17 can be adjusted, i.e. is selectable. By way ofthis, the user can control the delivery speed and—according theprocedure which is described in more detail hereafter—as the case may bethe preparation of cold frothed milk.

FIG. 23 shows an overview diagram of the milk frother appliance and itscoupling onto the drinks preparation machine (coffee machine 101). Airfeeds are indicated as “L” in the figure. The letter D indicates aconduit for steam, K a conduit for the hot drink, R a conduit forcleaning water or steam (optional) and S indicates the electricitysupply.

The activation 195 here is represented as part of an electronics unit121 of the coffee machine 101. The electronics unit 121 is configured,for example, to recognise a capsule by way of a measurement and/or toaccept a user input, for example via a suitable operating element with acorresponding button, with a touchscreen and/or the like.

Here, the activation 195 is designed such that it can activate the gearpump 7 as well as the valve unit 20, wherein an operating parameter ofthe gear and/or of the valve unit can be regulated (closed-loopcontrolled). Activation signals for the valve unit 20 and/or for thegear pump 7 run directly via the connection location 110.

An activation 195′ can also be present completely or partly as part ofthe milk frother appliance, alternatively to incorporating theactivation completely or partly in the coffee machine. This alternativeis represented in FIG. 20 in a dashed manner. The electrical energy and,as the case may be, data signals can then be transmitted from theelectronics unit to the activation 195′ via the alternative interface110′.

The mixing nozzle is indicated as a whole by the reference numeral 79.

The milk frother appliance can be operated as described hereinafter.

The gear pump is set in motion whilst at least one of the valve elementsof the valve unit 20 is open, for the preparation of cold frothed milk.A vacuum is produced at the inlet side of the gear pump due to theeffect of this pump, and this vacuum draws or sucks milk through themilk suction tube 18 and the corresponding duckbill valve 42, as well asair through the valve unit 20 and the corresponding duckbill valve 43.Milk froth therefore arises in the gear pump and gets through thefeed-through 36—whose narrowness encourages the formation of fine-poredfroth—, the outgoing conduit and the docking element 25, to the milkfroth outlet 28 and is dispensed there, wherein generally is drinksvessel 200 is placed upon the platform 103.

The drawing or sucking of the generally cold milk out of the milkcontainer 3 via the gear pump is also effected for the preparation ofwarm frothed milk. This gear pump delivers the milk into the mixingnozzle. Steam from the coffee machine is simultaneously fed to thisnozzle via the steam connection. As has already been explained above,the steam produces a vacuum, which, on the one hand, exerts anadditional suction upon the milk and assists in the delivery through thegear pump and, on the other hand, sucks air through the likewise atleast partly open valve element 20. In the mixing nozzle chamber 97, themilk is mixed with the steam, which heats it up and air issimultaneously intermixed, so that small air bubbles form and milk frotharises. The warm, frothed milk is dispensed through the milk frothoutlet.

As mentioned and depending on the situation, a 3/2-way valve or anothermeans can selectively connect the valve element 20 to the gear pump 7 orto the mixing nozzle chamber 97, for the production of cold and warmmilk froth respectively. As mentioned, it is also possible for the airfeed into the mixing nozzle chamber not to be effected via the valveelement 20 but in a direct manner, in which case the supply of aircannot then be regulated by way of a separate means when producing warmmilk froth.

One can also envisage the user also only being able to deliver coldmilk. In this case, the gear pump is driven, but the valve elementsremain closed, and also no steam is fed.

One can also envisage the user being able to prepare warm milk. In thiscase, the valve element, through which air can get into the mixingchamber, is closed. Should a separate valve for the mixing nozzlechamber be provided (differing from the embodiment represented in thefigures), then there is also the possibility of designing the respectivevalve in a closable manner. A closure of the valve can also be envisagedmechanically by the user by hand for example. For preparing warm milk,the milk is delivered out of the milk container 3 by way of the gearpump, and steam is simultaneously fed in the mixing nozzle 79, withoutair also being fed. Warm milk arises due to the mixing of the cold milkwith the steam, and this is then dispensed via the milk froth outlet 28.

For on-the-spot cleaning, a vessel is placed below the milk froth outlet28, and warm water or steam is fed through the feed-through conduit 96and the hot water and/or steam feed conduit 32. The gear pump issimultaneously set in motion.

The milk frother appliance, however, is also very simple to clean afterit has been removed. The milk container 3 and the lid 6 can be designedin a dishwasher-safe manner without any problems. The milk frothing unit5 can likewise be simple taken part and cleaned, wherein it is quiteuseful for the seal 21 to be designed as one piece with the duckbillvalves 41, 42, 43 and for it to terminate with the surface of the uppermain housing part 14 in a flush manner.

Finally, the docking element is simple to clean due to the fact that theparts that come into contact with milk (main body 25, supplementary part27) can be simply dismantled, designed in a dishwasher-safe manner andalso be simple assembled again in only a single—correct—configuration.

FIGS. 24 and 25 represent an alternative embodiment. This differs fromthe embodiment described above, in that the supply of air towards theair feed of the gear pump—thus, for example, to an air feed conduit 34,for example of the described type, or directly to the pump chamber—isnot effected by a valve unit belonging to the milk frother appliance,but in a manner coming from the drinks preparation machine. The drinkspreparation machine includes for example an electronically regulatedvalve unit for this purpose. This valve unit can be based essentially onthe same functioning principle as the valve unit of the milk frotherappliance which is described above. It can alternately have a differentfunctioning principle, for example by way of it only including one valveunit.

For this purpose, the docking element includes an air connection 151towards the drinks preparation machine. Air gets through an airfeed-through 152, which here horizontally passes through the dockingelement, into the milk frothing unit. In the represented embodimentexample, a section of the air feed-through is formed by a tube portion155 of the docking element housing 26, which however is not a necessity(concerning the air feed-through, a regular cleaning is not a necessity,in contrast to conduits, through which milk flows).

The possibility of the electrical contacts being able to be formed by acontact module 160 is yet indicated in FIG. 25, wherein this module, forexample, can include a circuit board or the like and be insertable intoa suitable recess in the docking element housing 26.

The valve unit arranged in the milk frothing unit is done away with inthe embodiment according to FIGS. 24 and 25.

Many further variants are conceivable. Apart from the options which havealready been discussed, there is also the possibility of keeping theconduits for cold milk froth (from the pump) and for warm milk froth(created in the mixing nozzle) separate from one another up to theoutlet, i.e. the cold milk froth is then not led through the mixingnozzle. The milk froth outlet can then include openings that areseparate from one another, for example concentric to one another, forthe cold and the warm milk froth. Milk froth outlets for the cold andthe warm milk froth and that are completely separate from one anotherare also conceivable, and the optional conditions for the maximaldistance between the milk froth outlet and the hot drinks outlet, whichare discussed above, apply in this case, for example, for the dischargeof the warm milk froth, since it is often this milk froth, which ismixed with the hot drink.

LIST OF REFERENCE NUMERALS

-   1 milk frother appliance-   3 milk container-   5 milk frothing unit-   6 lid-   7 gear pump-   11 lower main housing part-   12 window-   13 electric motor-   14 upper main housing part-   15 arching (in the milk frothing unit cover)-   16 milk frothing unit cover-   17 gears-   18 milk suction tube-   19 shaft-   20 valve unit-   21 seal-   22 connection shaped part-   23 spacer-   24 motor seal element-   25 main body (of the docking element)-   26 docking element housing-   27 supplementary part-   28 milk froth outlet-   29 end surface-   31 liquid conduit-   32 hot water and/or steam feed conduit-   34 air feed conduit-   35 outgoing conduit-   36 feed-through-   41 duckbill valve-   42 duckbill valve-   43 duckbill valve-   51 channel for hot water and/or steam feed conduit-   52 channel for air feed conduit-   53 channel for outgoing conduit-   61 valve housing-   62 closure element-   63 seal element-   64 electromagnet-   65 spring-   66 securing ring-   67 sealing portion-   68 seal-   71 valve chamber-   73 air connection stub-   79 mixing nozzle-   80 extensive sections-   81 joint-   82 air feed-through-   83 feed-through (for milk)-   84 feed-through for hot water or steam-   85 feed-through for steam-   86 feed-through for hot water or steam-   87 duckbill valve-   88 duckbill valve-   89 mixing nozzle element-   90 ring (structure) for positioning ring-   91 milk froth outlet continuation-   92 opening for the air feed-   93 opening for the milk feed-   94 positioning ring-   95 steam connection opening-   96 feed-through conduit-   97 mixing nozzle chamber-   98 (electrical) contacts-   99 mixing nozzle opening-   100 drinks preparation system-   101 coffee machine-   103 placement platform-   105 coffee outlet-   106 front-   107 milk frother platform-   108 outlet hood-   110 connection location-   110′ alternative interface-   111 steam delivery location-   112 hot water and/or steam delivery location-   113 electric contacts-   121 electronics unit-   151 air connection-   152 air feed-through-   155 tube portion-   195 activation-   195′ alternative activation-   200 drinks vessel

1. An appliance for preparing frothed milk, comprising a container forreceiving milk, and an electrically operated drive device for deliveringand/or frothing the milk, and a docking element for connection to adrinks preparation machine, said docking element comprising a connectionfor steam delivered by the drinks preparation machine; an interface forelectrical current that is supplied by the drinks preparation machineand is for operating the drive device; and a milk froth outlet for thefrothed milk.
 2. The appliance according to claim 1, wherein a distancebetween the milk froth outlet on the one hand and a plane of an endsurface of the docking element on the other hand, said end surfacecomprising the connection for steam and the electrical interface, ismaximal 2.5 cm.
 3. The appliance according to claim 1, wherein thedocking element is designed as a continuous, body-forming element, inwhose interior conduits for the milk and steam run.
 4. The applianceaccording to claim 3, wherein the docking element comprises a dockingelement that is designed as a shaped body of a plastic and forms atleast one conduit for milk.
 5. The appliance according to claim 3,wherein the docking element comprises a main body with a plurality offluid channels and a supplementary part, that is reversibly removablefrom the main body, wherein the supplementary part comprises a materialwhich is softer in comparison to the main body, said supplementary partbeing continuous and comprising several elements through which milk,steam, water and/or air can flow and which engage into the fluidchannels.
 6. The appliance according to claim 1, further comprising amilk frothing unit with a gear pump which at an inlet side is connectedto a milk feed conduit and to an air feed.
 7. The appliance according toclaim 1, further comprising a mixing nozzle, in which steam can bebrought together with the milk and air, wherein the mixing nozzle isarranged in the docking element and is arranged directly above the milkfroth outlet.
 8. The appliance according to claim 7, wherein the mixingnozzle is designed to exert a suction effect upon air and/or upon milkflowing into the mixing nozzle, on account of a flow of the steam. 9.The appliance according to claim 1, wherein the docking element furthercomprises a connection for cleaning water and/or cleaning steam whichis/are delivered by the drinks preparation machine, from whichconnection a cleaning water conduit and/or cleaning steam conduit passesthrough the docking element.
 10. A drinks preparation machine forpreparing a hot drink and for to which an appliance according to claim 1may be connected, comprising a delivery location for steam, for couplingonto the steam connection, and an electrical interface at the drinkspreparation machine side, for coupling onto the interface of theappliance, wherein the delivery location and thedrinks-preparation-machine-side interface are arranged such that theycan be contacted by the interface of the docking element.
 11. The drinkspreparation machine according to claim 10, wherein a drinks outlet forthe hot drink is arranged in direct proximity to the delivery location.12. The drinks preparation machine according to claim 10, comprising afront with a placement platform that projects from the front and is forreceiving a drinks vessel and with a drinks outlet hood projecting fromthe front above the placement platform, wherein a docking location withthe delivery location and with the drinks-preparation-machine-sideinterface is present laterally on the drinks outlet hood.
 13. A drinkspreparation system, comprising an appliance according to claim 1, aswell as a drinks preparation machine for preparing a hot drink and forto which the appliance 1 may be connected, said drinks preparationmachine comprising a delivery location for steam for coupling onto thesteam connection, and an electrical interface at the drinks preparationmachine side for coupling onto the interface of the appliance, whereinthe delivery location and the drinks-preparation-machine-side interfaceare arranged such that they can be contacted by the interface of thedocking element.
 14. The drinks preparation system according to claim13, wherein the drinks preparation system comprises a placement platformfor a drinks vessel, and in the docked-on condition of the appliance,the milk froth outlet as well as the drinks outlet of the drinkspreparation machine are arranged vertically above the placementplatform.
 15. The drinks preparation system according to claim 14,wherein a horizontal distance between the milk froth outlet and thedrinks outlet at the most is 5 cm in a docked condition.